Indexing tool for coiled tubing

ABSTRACT

An indexing tool for use with flexible coiled tubing in downhole applications to clear obstructions is provided. The indexing tool includes a housing having a central longitudinal bore. A plunger having a longitudinal axis and biased by a spring is received and movable longitudinally within the bore between retracted and extended positions. A channel formed on the plunger receives channel followers in the form of guide pins to cause the plunger to rotate about its longitudinal axis as the plunger is moved between the retracted and extended position. A limiting member of the plunger engages stop members to limit the movement of the plunger beyond the retracted and extended position, so the guide pins do not bear the longitudinal forces exerted on plunger. The guide pins are also provided with a head having a seating surface to facilitate tightening of the guide pins and to prevent further insertion of the guide pins.

TECHNICAL FIELD

[0001] The invention relates generally to downhole well tools, and particularly, to flexible coiled tubing for use in downhole applicaions, and more particularly to an indexing tool for use with coiled tubing.

BACKGROUND

[0002] Coiled steel tubing is a type of flexible tubing used in many oil and gas well applications. The coiled tubing is useful because long lengths of tubing can be conveniently wrapped around large reels. The reels of coiled tubing are easy to maintain and can be transported from place to place. Once the coiled tubing is taken to a particular job site, it can then be unspooled at the well location and run downhole to service the well. The coiled tubing typically comes in diameters of 1″, 1¼″, 1½″, and 1¾″.

[0003] When the coiled tubing is run downhole, it can sometimes encounter obstructions at remote locations which prevent it from further travel down the wellbore. To bypass these obstructions, the coiled tubing may be backed out of the wellbore a distance and lowered again in an attempt to direct the coiled tubing around the obstruction. A knuckle joint, which can be coupled to the coiled tubing and which allows some degree of angular rotation of the joined sections located at the end of the coiled tubing assembly, can be provided to facilitate clearing of the obstruction. Because of the remote location of most obstructions and difficulties in controlling the length of coiled tubing from the surface, this method, even when a knuckle joint is employed, often results in the coiled tubing reencountering the obstruction, so that several attempts may be made before the obstruction is eventually cleared. In some cases, because the knuckle joint merely allows the free relative rotation of the joined sections and does not provide any degree of control, it can even make clearing the obstruction more difficult in some cases.

[0004] There are devices for use with coiled tubing to assist in clearing such obstructions that provide more control. One such device, indicated at 2, is shown in FIG. 1. This device may be used for larger diameter coiled tubing of 1.7 inches or greater and is coupled to the end of the coiled tubing. Because of its larger size, however, it cannot be used with smaller diameter coiled tubing (e.g. 1½″ or less). This device utilizes a plunger 3 located within a housing 4 that is biased to an extended position by a coiled spring 5. When the length of coiled tubing with the indexing tool attached encounters an obstruction, the plunger 3 is depressed from the extended position. Guide pins 6 extending radially inward through the housing engage a non-axial channel 7 formed in the plunger to thereby rotate the plunger 3 as the plunger is moved to the retracted position and back to the extended position, or one cycle. The degree of rotation is usually small (60 degrees or less) for each cycle of the plunger. This can be repeated, with the plunger being rotated a full 360 degrees by repeated cycling of the plunger. Because the coiled tubing is usually non-linear, due to a certain degree of coil that remains in the coiled tubing length after it is unrolled, the rotation of the end of the coiled tubing assembly can cause the coiled tubing assembly near the obstruction to be reoriented to thus facilitate bypassing of the obstruction.

[0005] One of the shortcomings of the above-described indexing tool, other than its large size, is the amount of stress placed on and the potential failure of the guide pins 6. The guide pins used are unseated, headless set screws that are threaded generally along their entire length. Travel of the plunger is limited only by these set screws within the channel formed in the plunger. Thus, when the plunger is moved between the extended and retracted positions, the guide pins are the only structures or members that limit the plunger's movement. This places extraordinary loads and shearing forces on the guide pins. Additionally, because the set screws are headless and unseated, they can loosen or tighten during use. Thus, the set screw can loosen and disengage from the channel during use so that the plunger is no longer rotated during cycling. Alternatively, the set screw can tighten during use so that it engages the channel too tightly, preventing cycling and rotation of the plunger.

[0006] To overcome these and other shortcomings, improvements in such indexing devices are needed.

SUMMARY

[0007] An indexing device for use with coiled tubing in downhole applications for directing the tubing around downhole obstructions is provided. The device includes a housing adapted for securing to a length of coiled tubing. The housing has a longitudinal cylindrical internal bore. A plunger having a longitudinal axis is received within the internal bore and is moveable longitudinally within the internal bore between a retracted and extended position. The plunger has a channel that extends around at least a portion of the circumference of the plunger. The channel has opposite extents which are longitudinally spaced apart from each other.

[0008] A biasing member, which may be a coiled spring, is disposed within the housing for biasing the plunger toward one of the retracted and extended positions. The biasing member may exert a biasing force on the plunger of from 30 lbs to 100 lbs. A channel follower engages the channel as the plunger is moved between the retracted and extended positions. The channel follower causes the plunger to be rotated about the longitudinal axis as the plunger is moved between the retracted and extended positions. A limiting member is joined to the plunger.

[0009] First and second stop members each engage the limiting member when the plunger is moved between the extended and retracted positions, respectively. This prevents movement of the plunger beyond the extended and retracted positions. The channel follower is prevented from fully contacting the extents of the channel when the plunger is moved to the extended and retracted positions.

[0010] In certain, more specific, embodiments, a fluid passage is formed through the housing and plunger to allow the passage of fluid through the indexing device. The indexing device can also include a tool connector that is coupled to the plunger for coupling a desired tool to the indexing device. In one particular embodiment, the housing has width of from 1 to 1.5 inches. Cycling of the plunger from a first extended or retracted position to a second extended or retracted position, respectively, can cause the plunger to rotate about the longitudinal axis within a range of from 30 degrees to 120 degrees, and in a more specific embodiment, in a range from 72 degrees to 120 degrees.

[0011] And in one particular embodiment, the tool connector has a longitudinal axis that is at an angle of greater than zero degrees relative to the longitudinal axis of the plunger.

[0012] The channel follower, which may include at least two channel followers, may include a guide pin having a head and a shank extending from the head. The shank has a threaded portion, which is received within and engages an aperture formed in a wall of the housing, and a non-threaded channel engagement portion. The head of the guide pin has a stop flange that abuts against an exterior surface of the housing wall to limit insertion of the guide pin through the aperture and to facilitate securing of the guide pin within the aperture. The channel engagement portion projects from an interior surface of the housing into the internal bore. In one particular embodiment, the exterior surface of the housing wall has a recessed portion in communication with the aperture, with the head of the guide pin being received within the recessed portion.

[0013] A method for directing coiled tubing around a downhole obstruction is also provided. The method includes securing an indexing device to a length of the coiled tubing, wherein the indexing device includes:

[0014] a housing with a longitudinal cylindrical internal bore;

[0015] a plunger having a longitudinal axis that is received within the internal bore and is moveable longitudinally within the internal bore between a retracted and extended position, the plunger having a channel that extends around at least a portion of the circumference of the plunger, the channel having opposite extents which are longitudinally spaced apart from each other;

[0016] a biasing member disposed within the housing for biasing the plunger toward one of the retracted and extended positions;

[0017] a channel follower that engages the channel as the plunger is moved between the retracted and extended positions, the channel follower causing the plunger to be rotated about the longitudinal axis as the plunger is moved between the retracted and extended positions;

[0018] a limiting member joined to the plunger; and

[0019] first and second stop members that each engage the limiting member when the plunger is moved between the extended and retracted positions, respectively, so that movement of the plunger beyond the extended and retracted positions is prevented, and wherein the channel follower is prevented from fully contacting the extents of the channel when the plunger is moved to the extended and retracted positions.

[0020] A well tool is secured to the plunger of the indexing device. The coiled tubing assembly formed from the length of coiled tubing with the indexing device and well tool secured thereto is directed downhole within a wellbore until an obstruction is encountered. The coiled tubing assembly is alternately forced against the obstruction and retracted from the obstruction so that the plunger is cycled from a first extended or retracted position to a second extended or retracted position, respectively. The plunger is thereby rotated about the longitudinal axis to reorient the well tool secured thereto to bypass the obstruction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying figures, in which:

[0022]FIG. 1 is a longitudinal cross-sectional view of a prior art indexing tool;

[0023]FIG. 2 is a longitudinal cross-sectional view of a indexing tool, constructed in accordance with the invention;

[0024]FIG. 3 is an exploded, longitudinal cross-sectional view of a plunger housing of the indexing tool of FIG. 2, constructed in accordance with the invention;

[0025]FIG. 4 is a elevational view of a plunger of the indexing tool of FIG. 2, shown with a thrust bearing and coiled spring exploded away, and constructed in accordance with the invention;

[0026]FIG. 5 is an enlarged view of a guide pin exploded away from a guide pin aperture formed in the plunger housing of the indexing tool of FIG. 2, and constructed in accordance with the invention;

[0027]FIG. 6A is an enlarged view of a portion of the plunger of the indexing tool of FIG. 2, showing a channel of the plunger and the interrelation the guide pins with the channel when the plunger is in an extended position, in accordance with the present invention;

[0028]FIG. 6B is an enlarged view of the plunger of FIG. 6A, showing the plunger rotated approximately 45 when the plunger is in a retracted position and showing the interrelation of the guide pins with the channel, in accordance with the invention;

[0029]FIG. 7 is a longitudinal cross-sectional view of a connector used with the indexing tool of FIG. 2, and constructed in accordance with the invention; and

[0030]FIG. 8 is a longitudinal cross-sectional view of the indexing tool of FIG. 2, shown with the plunger in a retracted position.

DETAILED DESCRIPTION

[0031] Referring to FIG. 2, an indexing tool 10 constructed in accordance with the invention is shown. The indexing tool 10 is used primarily for use with flexible coiled steel tubing commonly used in downhole applications in oil and gas wells. The indexing tool 10 may be of a reduced width or diameter of less than 1.7 inches. As used herein, unless specified otherwise, the term “width” shall be taken to mean the greatest cross-sectional dimension. The indexing tool described herein and the dimensions given are for one having a reduced outer diameter or width of approximately 1¼ inches. Such dimensions are given for purposes of illustration only. As will be apparent to one skilled in the art, such dimensions can be varied while still maintaining an indexing tool of reduced diameter.

[0032] The indexing tool 10 includes a cylindrical main housing 12 having a longitudinal axis 14 and a longitudinal internal central bore 15. The housing 12 is preferably formed from steel or other suitable material, which has been machined or otherwise formed into the desired configuration. As shown in FIG. 3, the housing 12 is formed from an upper seal housing 16, a plunger housing 18 and a lower seal housing 20, each with an outer diameter of approximately 1¼ inches, that are coupled or joined together as described below. As used herein, the terms “upper,” “upward,” “lower” and “downward” are merely used for ease of description purposes and should not be construed in a limiting sense to a particular orientation of the indexing tool, as the indexing tool may be used in variety of different orientations where these terms could be inapplicable or even reversed. With reference to FIG. 2, where the indexing tool is shown in a horizontal position, however, the term “upper,” “upward,” and “above” shall refer generally to the direction towards the left of the figure, and “lower,” “downward” or “below” shall refer generally to the direction towards the right as shown in the figure.

[0033] As shown in FIG. 3, the upper end of the upper seal housing 16 is provided with an externally threaded end portion 22 which acts as a male coupling having helical screw threads for engaging mating threads on a “1¼ inch” connector (not shown) of the of steel tubing or another service tool (not shown) coupled to the coiled tubing assembly. Preferably, the end portion 22 is of standard commercial design and size for coupling to standard fittings and connectors used with flexible tubing. The end portion 22 may also be configured as a female coupling as well. The lower end of seal housing 16 is provided with an internal threaded portion 24.

[0034] The upper end of the plunger housing 16 is provided with an externally threaded end portion 26 that is received within and engages the threaded portion 24 of upper housing 16 so that the upper housing 16 and plunger housing 18 are joined together. The lower end of the plunger housing 16 is also proved with an externally threaded end portion 28.

[0035] The lower seal housing 20 has an upper end portion 30 that has internal threads for engaging the threaded end portion 28 of the plunger housing 18 so that the plunger housing and lower seal housing 20 are joined together.

[0036] Referring to FIG. 4, a plunger 32 is shown. The plunger 32 is preferably a single piece of machined steel or other suitable material having a longitudinal axis that is parallel and preferably coaxial with the longitudinal axis 14 of the housing 12. The plunger 32 consists of a main plunger body 34 which is generally cylindrical in shape having a generally uniform cross-sectional diameter. In the particular embodiment shown, the cross-sectional diameter of the plunger body 34 is approximately 0.865 inches, and has a cross-sectional diameter or width that is less than the greatest cross-sectional diameter or width of the plunger 32. A cylindrical sleeve 36 of smaller diameter (O.D.=0.59 inches) extends upward from the plunger body 34. Formed on the lower end of the plunger body 34 is a travel limiting member 38. The limiting member 38 extends radially outward from the plunger body 34 and has an upper annular face 38A and lower annular face 38B. The upper and lower annular faces 38A, 38B are spaced apart approximately 0.375 inches. In the embodiment shown, the limiting member 38 is a cylindrical annular ring integrally formed with the body 34, and which has a larger diameter (0.99 inches) than the main plunger body 34.

[0037] Extending downward from the plunger body 34 is a cylindrical plunger shaft 40 (OD=0.75 inches), which extends downward and terminates in an externally threaded portion 42. Formed above the threaded portion 42 are opposite flats 44 for accommodating a wrench or similar tool to grasp the plunger 32 to hold it in place when coupling to a well tool or other coupling. A longitudinal flow passage 46 having a diameter of approximately ⅜ inches is formed through the entire length of the plunger 32 to allow passage of fluids therethrough.

[0038] As shown in FIG. 2, the plunger 32 is received within the internal bore 15 of the housing 12. When housed therein, the limiting member 38 locates within the lower seal housing 20, which has an internal bore 47 of approximately 1 inch diameter. The lower seal housing 20 is also provided with an inwardly projecting internal annular shoulder 48 or annular stop member, which projects from the internal bore 47 approximately 0.118 inches, against which the lower face 38B of the limiting member 38 abuts when the plunger is in a fully extended position. With the plunger housing 18 coupled to the lower seal housing 20, the annular lip 50 formed on the end of the lower portion 28 of the plunger housing 18 serves as a shoulder or annular stop member against which the upper face 38A of limiting member 38 abuts when the plunger is in a fully retracted position. The lip 50 may have a width of from about 0.04 to about 0.07 inches. As can be seen, the stop members 48, 50 are axially spaced apart a distance to allow travel of the limiting member 38 therebetween. In the embodiment shown, the stop members 48, 50 are spaced apart approximately 1.375 inches so that the plunger travel between the extended and retracted positions is approximately one inch.

[0039] The plunger shaft 40 extends through bore 52 (I.D.=0.765 inches) of lower seal housing 20 to the exterior of the housing 12. Formed in the bore 52 are a pair of axially spaced apart annular recesses 54, 56 for receiving O-rings or annular seals 58, 60, which each sealingly engage the exterior of the plunger shaft 40 to prevent the ingress of fluids into the central bore 15 through the bore 52 of the lower seal housing.

[0040] Formed in the upper end of the upper seal housing 16 is a fluid passage 62 having a diameter of about {fraction (7/16)} inches. The fluid passage 62 opens into and communicates with larger central bore 64 (I.D.=0.625 inches) of the housing 16, which opens into central bore 74 of the plunger housing 18 when the housing 16 and 18 are coupled together. As can be seen in FIG. 2, the upper sleeve 36 of the plunger 32 extends into the central bore 64. The central bore 64 is of sufficient length to accommodate the sleeve 36 of the plunger 32 when the plunger is moved between the extended and retracted positions. Annular recesses or slots 66, 68 formed in the interior wall of the central bore 64 are provided and receive O-ring or annular seals 70, 72 and sealingly engage the exterior of the sleeve 36. The seals 70, 72 prevent the passage of fluid past to the central bore 74 of the plunger housing 18 so that fluid from the passage 62 flows into passage 46 of the plunger 32.

[0041] Located within the central bore 74 of the plunger housing 18 is a compressed steel coiled spring 76, which surrounds the sleeve 36 of the plunger 32. The spring 76, as shown in FIG. 4, is a coiled steel compression spring having a constant body diameter and closed and ground ends so that each end has a generally flush profile. Coiled springs with plain and/or non-closed ends could be used as well. The spring should be selected to provide free contraction and expansion of the coils within the housing and about the sleeve 36 without binding. Preferably, the pitch or spacing between the coils is sufficient so that the coils do not touch or otherwise engage one another during operation of the indexing tool. The spring should exert enough force upon the plunger 32 so that it provides sufficient rigidity to the indexing tool 10 during normal operation of the coiled tubing assembly, but that will compress when encountering impenetrable obstructions or obstacles encountered within the wellbore. A spring that provides from 30 to 100 lbs of resistance is suitable in most instances.

[0042] In the particular embodiment shown for a 1¼ inch indexing tool, the spring 76 is formed from 0.110 inch diameter steel wire having an uncompressed free length of 3.830 inches and approximately 13.5 active coils, with a load rate of about 40 lbs/inch. The spring 76 has an inner diameter of approximately 0.625 inches to accommodate the upper sleeve 36 and an outer diameter of about 0.83 inches. The spring 76 is compressed by about one inch so that it has a length of about 2.830 inches when installed and is preloaded with 40 lbs of biasing force. When installed, the upper end of the spring 76 abuts against an interiorly projecting annular shoulder 78 formed by the termination of the bore 64 and proximate to where the threaded portion 24 joins the remainder of the upper seal housing 16. The lower end of the spring 76 abuts against an annular thrust bearing 80, through which the sleeve 36 extends and which abuts against an annular shoulder 82 formed on the plunger body 34 where the plunger body 34 adjoins the sleeve 36. The thrust bearing 80 has an outer diameter of about 0.855 inches and an inner diameter of about 0.65 inches. The spring 76 biases the plunger 32 to its extended position. When the plunger 32 is moved to the retracted position, the plunger 32 will compress the spring 76 approximately one inch so that the spring provides a biasing force of about 80 lbs at the fully retracted position.

[0043] Referring to FIG. 5, formed in the plunger housing 18 wall are guide pin apertures 84 for receiving guide pins 86. In the embodiment shown, there are two apertures 84 circumferentially spaced apart approximately 180 degrees. Each guide pin 86 has a head 88 and a shank 90. The shank 90 is provided with a threaded portion 92 and a non-threaded channel engagement portion 94 on the end of the shank 90 opposite the head 88 having a diameter of 0.155 inches and a length of about 0.125 inches. The head 88 is provided with a slot 95 or is otherwise configured to receive a tool to facilitate tightening or loosening of the guide pin. A sloped stop face or flange 89 is provided on the underside of the head 88.

[0044] Each aperture 84 is configured to receive a guide pin 86 and is provided with an internally threaded portion 96 that engages the threaded portion 92 of the shank 90. A recessed guide pin seat 98 having a sloped seating surface that extends radially outward from the threaded portion 96 towards the exterior of the plunger housing is provided. When the guide pin 86 is threaded into the aperture 84, the seating face 89 formed on the lower portion of the head 88 of the pin 86 seats or abuts against the guide pin seat 98 to prevent further insertion of the guide pin 86 into the aperture 84, and to facilitate tightening of the guide pin 86 within the aperture 84 so that it cannot inadvertently loosen.

[0045] When the guide pin 86 is fully engaged and seated within the aperture 84, the head 88 of the guide pin 86 is preferably flush with the exterior surface of the plunger housing 18. When so seated, the channel engagement portion 94 will extend beyond the interior wall of the plunger housing 18 where it is received within a channel 100 formed in the plunger body 34.

[0046] The channel 100 extends around the entire circumference of the plunger body 34 and is configured so that the plunger 32 is rotated by engagement with the guide pins 86 within the channel 100 as the plunger 32 is moved between extended and retracted positions. The channel 100 is of sufficient width and depth to accommodate the engagement portion 94 of the guide pins 86. As can be seen in FIGS. 6A and 6B, the channel 100 is formed from parallel upper and lower longitudinal sections 102, 104, respectively, which are circumferentially spaced apart and are repeated about the perimeter of the plunger body 34. The upper section 102 terminates at its uppermost end at an upper extent 106, and the lower section 104 terminates at its lowermost end at a lower extent 108. The upper and lower sections 102, 104 are connected by upward and downward sloped sections 110, 112, which extend circumferentially about the plunger body 34 and which have opposite upward and downwardly sloping walls 114, 116, respectively.

[0047] The lower section 104 terminates at its upper end at the sloped wall 114, which extends generally across the width of the lower section 104. In a similar manner, the upper section 102 terminates at its lower end at the sloped wall 116, which extends generally across the width of the upper section 102. The angle of the upward and downward sloping walls 114, 116 relative to the longitudinal axis of the plunger 32 may vary depending upon the length of plunger travel and the desired degree of rotation of the plunger 32 during cycling. Preferably, the sloped walls 114, 116 are at an angle of at least 135 degrees relative to the longitudinal axis of the plunger 32 to facilitate rotation of the plunger and to prevent the possibility of the guide pins 86 from catching or locking along the walls 114, 116. The sections of the channel 100 are also oriented and configured to prevent the plunger 32 from being rotated in the reverse direction when moved between the retracted and extended positions.

[0048] The indexing tool 10 can also include a tool connector 118, shown in FIG. 7. In the embodiment shown, the connector 118 is a 1¼ inch diameter connector. The connector 118 includes a connector body 120 having a central bore or flow passage 122. The lower end of the connector body 120 is provided with an internally threaded recessed connector portion 124 that is in communication with the passage 122, and which is preferably of standard commercial design and size for coupling to standard fittings and connectors used with flexible tubing. The connector portion 124 may also be configured as a male coupling, as well, with the flow passage 122 extending therethrough.

[0049] The upper end of the connector body 120 is provided with an internally recessed portion 126 or female coupling that communicates with the passage 122 and has internal helical annular threads formed thereon for receiving the threaded end portion 42 of plunger 32. Alternatively, as would be apparent to those skilled in the art, the portion 126 of the connector body could be a male coupling and the end portion 42 of the plunger 32 could be a female coupling. An annular recess 128 is provided in the recessed portion 126 for accommodating an annular seal or O-ring 130 which engages the threaded portion 42 of plunger 32 to prevent loss of fluid through the coupling from passage 122.

[0050] The recessed portion 126 may have a longitudinal axis that is parallel with the longitudinal axis of the connector portion 124. In the particular embodiment shown, however, the longitudinal axis of the recessed portion 126 is at an angle of approximately 2° with respect to the connector portion 124 so that the connector portion 124 is offset. Thus, when the connector body 120 is coupled to the plunger 32, the longitudinal axis of the portion 126 will be parallel with the longitudinal axis 14. The longitudinal axis of the connector portion 124, however, may be non-parallel, and in this instance is at an angle A of approximately 2° with respect to the longitudinal axis 14. This angle may be varied, however, anywhere from greater than zero degrees to 45° or more. The angle A may be limited to very shallow angles, however, due to the constricted spaces within wellbores and depending upon the length of attachments attached to the tubing assembly at the connector portion 124. Longer well tools attached to the connector 118 will typically require a shallower angle A. The angle A may be greater than 0° to about 10°, with from 1° to about 5° being suitable in many instances. In this way, the service tool or other tool assembly coupled to the connector 118 will be at a slight angle with respect to the longitudinal axis of the indexing tool 10.

[0051] The indexing tool 10 is used as follows. The flexible tubing assembly, comprised of the length of flexible tubing (not shown), the indexing tool 10 with an attached well tool (now shown), as well as any other components or tools, such as valves, etc., coupled to the tubing string, is lowered into a well bore. The indexing tool 10 may be coupled directly to a length of flexible coiled tubing (not shown) or another component of the tubing string at the end 22. A desired well or service tool (not shown) is coupled at the opposite end of the indexing tool 10 through the connector 118. Based upon the length of the service tool (not shown) and the width of the well bore, the connector 118 may have to be selected with an appropriate angle A to provide sufficient clearance and passage of the indexing tool and attached tool therethrough. Preferably, the indexing tool 10 is placed at the end of the tubing string adjacent to or near proximity to the well tool located at the very end of the tubing string. The flow passage of the indexing tool 10 created by the fluid passage 62, flow passages 46 and 122, of the plunger 32 and connector 118, respectively, allows fluid to flow through the indexing tool 10 from the flexible tubing or other component attached at 22 to the well tool attached at connector 118.

[0052] During normal operation, the plunger 32 of the indexing tool will remain in the extended position, as shown in FIG. 2. In the extended position, the lower face 38B of the limiting member 38 engages the shoulder 48 of lower seal housing 20, which prevents further downward movement of the plunger 32 relative to the housing 12. Each of the guide pins 86 will engage a similar corresponding or matching section of the channel 100, which is circumferentially spaced apart from the other so that the relative movement of the guide pins 86 within the channel 100 will be essentially the same. When in the fully extended position, the end portions 94 of guide pins 86 are spaced from or may lightly touch the upper extent 106 of the channel, so that the pins 86 do not fully engage the upper extent 106. This is beneficial in that that the full force exerted against the plunger 32 by the spring 76 is not born or transmitted to the guide pins 86 to limit the movement of the plunger 32 beyond the extended position, as in the prior art. Instead, the force is born primarily, if not entirely, by the shoulder 48, which is integrally formed with the lower housing 20.

[0053] As the tubing assembly is lowered or otherwise directed through the well bore, any obstruction encountered by the well tool located at the end of the tubing string will cause the plunger 32 to be moved toward the retracted position. As this occurs, the guide pins 86 will engage and ride along the wall 116, which is sloped downward, thus causing the plunger 32 to be rotated. Upon further movement of the plunger 32 toward the retracted position, the guide pins 86 will pass into one of the lower longitudinal sections 104 toward the lower extent 108.

[0054] As the plunger 32 is moved upward within the housing 12, the upper face 38A of the limiting member 38 will engage or contact the lip or shoulder 50, which acts as a stop member for preventing further movement of the plunger 32 beyond the retracted position. When in the fully retracted position, as shown in FIGS. 6B and 8, the end portions 94 of guide pins 86 are spaced from or may lightly touch the lower extent 108 of the channel 100, so that the pins 86 do not fully engage the lower extent 106. Again, upward forces exerted against the plunger 32 are therefore not born by the guide pins 86 to limit the movement of the plunger 32 beyond the retracted position, as in the prior art. Instead, the force is transmitted primarily, if not entirely, to the lip 50 of the plunger housing 18.

[0055] When the coiled tubing assembly is retracted to reduce the force exerted on the plunger 32, the plunger 32 will begin moving toward the extended position. As this occurs, the guide pins 86 will engage or ride along the upward-sloped wall 114 of section 110 of the channel 100. This causes the plunger 32 to be rotated still further about its longitudinal axis as the guide pins 86 travel along the wall 114. Eventually, the guide pins 86 enter the upper longitudinal section 102, allowing the plunger 32 to move to another fully extended position.

[0056] The amount of rotation of the plunger 32 with each cycle will vary depending upon the configuration of the channel 100 and the length of travel of the plunger 32 between the fully extended and retracted positions. This due to the angle of the sloped walls 114, 116, where axial movement of the plunger is translated into rotational movement. The steeper the angle of the walls 114, 116, the less force is required to rotate the plunger 32. Shallower angles require more force to rotate the plunger, thus requiring a stronger spring 76.

[0057] In most configurations, the amount of rotation for each cycle of the plunger will be from about 30 degrees to 120 degrees. A range of from about 72 degrees to about 120 degrees is particularly well suited for most applications. In the particular embodiment shown, the amount of rotation is approximately 90 degrees for each cycle of the plunger.

[0058] As the plunger 32 is rotated, the connector 118 with offset connector portion 124 is rotated. The offset of the connector portion 124 causes the attached tool (not shown) to be reoriented to facilitate clearing of the encountered downhole obstruction. Repeated cycling of the plunger 32 reorients the attached tool to further facilitate clearing of the obstruction, if necessary. In this way, the plunger can be rotated an entire 360 degrees.

[0059] Because of its design, the indexing tool can be made with a smaller diameter (i.e. less than 1.7 inches) than the prior art indexing tools, allowing it to be used with smaller diameter flexible coiled tubing. The use of the limiting member and stop members to limit movement of the plunger beyond the extended and retracted positions limits the amount of force applied to the guide pins. This prevents the guide pins from failing or shearing off, as the prior art pins are prone to do. Further, because the guide pins bear much less force, they may be made smaller, facilitating a smaller diameter indexing tool design.

[0060] Because the guide pins are provided with a head having a stop flange, the guide pins can be securely seated and tightened within the apertures formed in the housing wall. In contrast to the headless set screws used for the prior art guide pins, this ensures that the guide pins do not loosen or become lost. Further, the guide pins are prevented from threading further into the housing aperture, where they can bear upon the channels of the plunger so that the plunger becomes locked in place.

[0061] While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the scope of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention. 

I claim:
 1. An indexing device for use with coiled tubing in downhole applications for directing the tubing around downhole obstructions, the device comprising: a housing adapted for securing to a length of coiled tubing, the housing having a longitudinal cylindrical internal bore; a plunger having a longitudinal axis that is received within the internal bore and is moveable longitudinally within the internal bore between a retracted and extended position, the plunger having a channel that extends around at least a portion of the circumference of the plunger, the channel having opposite extents which are longitudinally spaced apart from each other; a biasing member disposed within the housing for biasing the plunger toward one of the retracted and extended positions; a channel follower that engages the channel as the plunger is moved between the retracted and extended positions, the channel follower causing the plunger to be rotated about the longitudinal axis as the plunger is moved between the retracted and extended positions; a limiting member joined to the plunger; and first and second stop members that each engage the limiting member when the plunger is moved between the extended and retracted positions, respectively, so that movement of the plunger beyond the extended and retracted positions is prevented, and wherein the channel follower is prevented from fully contacting the extents of the channel when the plunger is moved to the extended and retracted positions.
 2. The device of claim 1, wherein: a fluid passage is formed through the housing and plunger to allow the passage of fluid through the indexing device.
 3. The device of claim 1, further comprising: a tool connector that is coupled to the plunger for coupling a desired tool to the indexing device.
 4. The device of claim 1, wherein: the housing has width of from 1 to 1.5 inches.
 5. The device of claim 1, wherein: cycling of the plunger from a first extended or retracted position to a second extended or retracted position, respectively, causes the plunger to rotate about the longitudinal axis within a range of from 30 degrees to 120 degrees.
 6. The device of claim 5, wherein: the range is from 72 degrees to 120 degrees.
 7. The device of claim 1, wherein: the tool connector has a longitudinal axis that is at an angle of greater than zero degrees relative to the longitudinal axis of the plunger.
 8. The device of claim 1, wherein: the channel follower includes a guide pin having a head and a shank extending from the head, the shank having a threaded portion, which is received within and engages an aperture formed in a wall of the housing, and a non-threaded channel engagement portion, the head of the guide pin having a stop flange that abuts against an exterior surface of the housing wall to limit insertion of the guide pin through the aperture and to facilitate securing of the guide pin within the aperture, the channel engagement portion projecting from an interior surface of the housing into the internal bore.
 9. The device of claim 8, wherein: the exterior surface of the housing wall has a recessed portion in communication with the aperture, the head of the guide pin being received within the recessed portion.
 10. The device of claim 1, wherein: the biasing member is a coiled spring.
 11. The device of claim 1, wherein: the biasing member exerts a biasing force on the plunger of from 30 lbs to 100 lbs.
 12. The device of claim 1, wherein: there are two channel followers.
 13. A method for directing coiled tubing around a downhole obstruction, the method comprising: securing an indexing device to a length of the coiled tubing, wherein the indexing device includes: (a) a housing with a longitudinal cylindrical internal bore; (b) a plunger having a longitudinal axis that is received within the internal bore and is moveable longitudinally within the internal bore between a retracted and extended position, the plunger having a channel that extends around at least a portion of the circumference of the plunger, the channel having opposite extents which are longitudinally spaced apart from each other; (c) a biasing member disposed within the housing for biasing the plunger toward one of the retracted and extended positions; (d) a channel follower that engages the channel as the plunger is moved between the retracted and extended positions, the channel follower causing the plunger to be rotated about the longitudinal axis as the plunger is moved between the retracted and extended positions; (e) a limiting member joined to the plunger; and (f) first and second stop members that each engage the limiting member when the plunger is moved between the extended and retracted positions, respectively, so that movement of the plunger beyond the extended and retracted positions is prevented, and wherein the channel follower is prevented from fully contacting the extents of the channel when the plunger is moved to the extended and retracted positions; securing a well tool to the plunger of the indexing device; directing the coiled tubing assembly formed from the length of coiled tubing with the indexing device and well tool secured thereto downhole within a wellbore until an obstruction is encountered; and alternately forcing the coiled tubing assembly against the obstruction and retracting the coiled tubing assembly from the obstruction so that the plunger is cycled from a first extended or retracted position to a second extended or retracted position, respectively, and wherein the plunger is rotated about the longitudinal axis to reorient the well tool secured thereto to bypass the obstruction. 